Various foods, glass products such as lenses, leather products such as leather boots, leather jumpers and fur coats and products of paints and pastes formed of starch or cellulose are apt to mold. This considerably reduces validity of the goods or calls for waste disposal thereof.
Apart from mold, increased growth of harmful microorganisms, too, considerably reduces validity of the goods or demands for waste disposal thereof. For example, in the case of foods, there are caused problems of fermentation and food poisoning due to increased growth of bacteria.
It is known to seal-pack an article together with an oxygen absorber with a packing material and to maintain the oxygen concentration within the pack below 1% or less for the purpose of preventing the article from molding. While this method can effectively prevent generation of mold by aerobic bacteria, this cannot be an effective means for preventing increase and growth of anaerobic bacteria which account for food poisoning or fermentation.
It is also known to seal-pack an article together with an ethanol-emanating agent and to fill the inside of the pack with ethanol vapors for the purpose of preventing the formation of mold and the growth of ordinary bacteria. With this method, satisfactory effect cannot be obtained unless ethanol which is expensive is used in a relatively large amount.
Further, a number of mildew-proofing agents and anti-bacterial agents are hitherto known. Most of these chemicals, however, have toxicity to human bodies so that the use thereof is subjected to severe restriction.
A number of natural products having an antimicrobial action are hitherto known. Especially, Eutrema wasabi is known to have an excellent germicidal activity. It is also known to subject food to a germ-destroying treatment using an isothiocyanate (hereinafter referred to simply as ISOTC) which is a major component of wasabi. For example, Japanese Published Unexamined Patent Application No. Sho-57-99182 discloses an aqueous emulsion composition obtained by emulsion-dispersing, in water in the presence of an emulsifier, a solution of ISOTC dissolved in an oil. This aqueous emulsion composition is used by mixing into a food so as to sterilizing the food. However, the incorporation of such an aqueous emulsion into foods is not preferable not only because taste of the foods deteriorates but also because ISOTC in foods is apt to decompose. Japanese Published Unexamined Patent Application No. Sho-58-63348 discloses a method for Preserving vegetables and fruits wherein the vegetables and fruits are packed in a packaging vessel together with a synthetic zeolite which has a pore diameter of 5-10 .ANG. and which is impregnated with ISOTC in a proportion of about 5% by weight. The ISOTC-impregnated zeolite does not emanate an effective amount of ISOTC vapors in air. It can adsorb moisture in air when subjected to a high humidity condition of a relative humidity of 90% or more with the simultaneous generation of ISOTC adsorbed therein. This known method has problems because the synthetic zeolite with a pore diameter of 5-10 .ANG. to be used as an absorbent of ISOTC is expensive and because the amount of ISOTC adsorbed thereto is very low of about 5% by weight. The known, ISOTC-absorbed, synthetic zeolite has also a drawback because it cannot emanate ISOTC vapors unless it is subjected to a high humidity condition. Thus, the ISOTC-adsorbed, synthetic zeolite is not effectively utilized as a general ISOTC vapor-generating agent.
As described in the foregoing, several techniques for destroying germs with the use of ISOTC which is a major ingredient of wasabi are known. However, none of them are not satisfactory from the practical standpoint.
It is the prime object of the present invention to provide an easy to handle, ISOTC vapor-generating agent utilizing ISOTC which is a major ingredient of wasabi and various products containing such an agent.
Another object of the present invention is to provide a method for germ-destroying treatment of various articles using ISOTC vapors.
It is a further object of the present invention to provide an apparatus for carrying out germ-destroying treatment using ISOTC.
The present inventors have made various studies in order to accomplish the above objects and, as a result, have found, on the basis of payment of attention to the fact that ISOTC is an oily liquid, that the amount of ISOTC generated can be advantageously and finely controlled by controlling the concentration of ISOTC in a solution obtained by dissolving ISOTC in an oily liquid having a vapor pressure at 30.degree. C. of 2 mmHg or less and that germ-destroying treatment of various articles can be effectively advantageously performed, without encountering any noticeable deterioration of working environments by contacting the various articles with ISOTC vapors generated from the solution.
The present inventors have also found that an easy to handle ISOTC-vapor generating agent capable of generating ISOTC vapors in a controlled amount is obtainable by impregnating a porous adsorbent with the above ISOTC solution.
The present inventors have further found that an easy to handle ISOTC-vapor generating agent capable of generating ISOTC vapors in a controlled amount is obtainable by incorporating the above ISOTC solution into a gel-like substance or by encapsulation thereof.
The present inventors have further found that various products with germ-destroying action is obtainable by using the above-mentioned ISOTC vapor-generating agent.
The present inventors have further found that plastic films such as polyethylene films and polypropylene films have a high gas-permeability to ISOTC vapors and that an article can be effectively treated for destroying germs when seal-packed with such a plastic film and when contacted with ISOTC vapors.